Eckerite is a very rare silver-copper arsenic sulfide mineral found in hydrothermal vein systems. It typically occurs as massive aggregates associated with other silver sulfosalts and is primarily sought after by advanced mineral collectors specializing in rare species.
Is this eckerite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch eckerite with a known reference. Eckerite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: orange-red.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine to metallic.
- 4Match the color rangeCompare against the expected color range: red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
Often confused with
Eckerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Eckerite leaves orange-red, Polybasite leaves black; luster reads adamantine to metallic on Eckerite and metallic on Polybasite.
How to tell apart: Streak differs, so Eckerite leaves orange-red, Pearceite leaves black; luster reads adamantine to metallic on Eckerite and metallic on Pearceite.
Often found alongside eckerite
Minerals reported to co-occur with eckerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₂CuAsS₃
- Mohs hardness
- 2.5-3
- Density
- 5.313 g/cm³
- Colors
- Streak
- Orange-red
- Luster
- Adamantine to metallic
- Transparency
- Transparent to opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In massive to interstitial sulfosalt accumulations in dolostones metamorphosed to upper greenschist to lower amphibolite facies
Where rockhounds find eckerite
Classic worldwide localities
- Lengenbach quarry, Binn Valley, Valais, Switzerland
Field-hunting tip
Where it forms: In massive to interstitial sulfosalt accumulations in dolostones metamorphosed to upper greenschist to lower amphibolite facies. If you start seeing realgar, sinnerite, hatchite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify eckerite?+
Where is eckerite found?+
Is eckerite safe to handle?+
What rocks look like eckerite?+
What minerals are found with eckerite?+
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Find eckerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
